CCR FAQ - O2ptima-SR

©Copyright by Mark Derrick, Dive Gear Express staff O2ptima CCR Instructor

How much does an O2ptima-SR cost?

A better wording of the question might be 'How much does it cost to switch from an open-circuit diver to an O2ptima CCR diver?' In addition to a complete ready-to-dive O2ptima-SR you will need off board bailout and an initial stock of consumables. Training, particularly if travel is required, will be a significant cost. I suggest planning on a total amount from $10,000 to $12,000. These are estimates, the total could be less or more depending on where you live, what suitable equipment you already have, and what additional equipment you might choose to purchase.

How long does it take to get an O2ptima-SR rebreather?

O2ptima rebreathers with Shearwater Electronics, along with all options, accessories and spares are usually in-stock for immediate shipment. Occasionally, demand or logistics will cause brief stock-outs of the base O2ptima unit but delays beyond 30 days are rare.

How much does the O2ptima training cost?

There is wide variation in CCR training costs due to a variety of factors, although location is often a major influence. There is now a geographically diverse group of instructors and you might have an O2ptima instructor in your local area. Typically, the cost is $1500 for instruction only. If you prefer to learn about your O2ptima at Dive Gear Express in Pompano Beach Florida, training can be organized to accommodate your schedule and rebreather courses run every month. Dive Gear Express offers an all inclusive version which includes the cost of pool rental, consumables, teaching materials, boat charters, and so on for a price of $2000.

How much does O2ptima routine maintenance cost?

You should budget routine maintenance costs of approximately $500 annually. The manufacturer recommends the canister O-ring set, wiring harness, mushroom valves and four oxygen sensors be replaced annually. They also recommend the first stage regulators be serviced every 18 months or 100 dives, although I recommend the oxygen regulator be serviced more frequently. You will also need to replenish minor consumables such as lubricant and disinfectant from the annual maintenance budget.

What consumables do you recommend for the O2ptima-SR?

The recommended consumables are: Micropore ExtendAir CO2 absorbent cartridge model 101C, Steramine solution for breathing loop disinfection, Tribolube 71 lubricant for O-ring seals, and Caig Labs DeoxIT GOLD for cleaning gold electrical contacts. The Shearwater electronics require a total of three batteries. The recommended batteries for the handset and hud are one each of primary AA sized Energizer 1.5V Photo Lithium or SAFT 3.6V LS15400 Lithium, but they can use a variety of other AA sized primary batteries in a pinch. The solenoid battery is a primary alkaline 9V size (6LR61) such as a consumer grade Energizer or Duracell. The O2ptima-SR uses four industry standard diving grade 10mv-in-air oxygen sensors with 3-pin Molex style connectors often referred to as R-22D type sensors. The Analytical Industries brand PSR-11-39-MD diving grade oxygen sensors are recommended.

How much do the O2ptima consumables cost?

As with all rebreathers, the major consumable cost is CO2 absorbent. An O2ptima absorbent cartridge is about $35 and typically can be used for several dives, but there are other smaller costs such as batteries and gas fills. Keep in mind that for both open-circuit and rebreather divers, consumables costs are usually insignificant in relationship to the investment in the equipment, training and other diving costs such as boat charters and travel.

How long do the O2ptima-SR consumables last?

Experienced O2ptima-SR sport divers, when tracking their CO2 production by monitoring their O2 consumption, are reporting scrubber duration in the range of four to six hours and battery duration of thirty to fifty hours. The duration in actual use depends upon many factors related to the individual diver, specific dive conditions and particular brands of consumables. These are observations of what experienced divers are reporting and in no way suggests exceeding manufacturer recommendations or that novices should expect these durations.

Click Here to read O2ptima Rebreather Scrubber Duration Test Results.

Why does the O2ptima use a cartridge CO2 absorbent instead of granular?

The O2ptima rebreather is designed to use the ExtendAir Cartridge CO2 absorbent manufactured by Micropore. ExtendAir cartridges solve many of the problems associated with traditional granular carbon dioxide absorbents. ExtendAir absorbents use the same chemistry as granular absorbents but in the form of easy-to-use cartridges that are quickly loaded into the scrubber canister (even under adverse conditions). The individually sealed cartridges need only be opened immediately prior to use and are date stamped to assure freshness. ExtendAir cartridges eliminate problems of channelling and duration variability associated with granular absorbents because they eliminate both settling and individual differences in canister filling technique. ExtendAir cartridges also eliminate the problem of absorbent dust contamination in the breathing loop. The O2ptima scrubber is more compact and light weight than granular adsorbent scrubbers, because ExtendAir cartridges are more efficient with more consistent performance.

Is the O2ptima CO2 absorbent cartridge more expensive than granular?

Compared to granular, the cartridge costs about $5 more per hour of sport diving using a duration of three hours and less with longer duration. But even assuming the cartridge is more expensive than granular, this is justified because the cartridge absorbent offers important and valuable advantages over granular.

What about the possibility of a 'caustic cocktail' with the O2ptima?

Inhaling a mixture of CO2 absorbent and water while diving with an O2ptima is very unlikely. The O2ptima is a modern CCR design that includes several features to manage and remove water from the breathing loop. The O2ptima cartridge also eliminates granular absorbent dust contamination, even further diminishing the risks. The 'caustic cocktail' is a concern from an earlier era of rebreather diving that has been overly dramatized, akin to the concern new divers express regarding 'shark attack'.

How available is the O2ptima CO2 absorbent?

Micropore, the US manufacturer of the Extendair absorbent, has several strategically located warehouse distribution centers. In the global economy, absorbents are sold and shipped all over the world. As a result, supply logistics for absorbent is becoming less of an issue. The number of dive shops that stock absorbent is consistently growing, and you can always order on-line to be delivered to your door or directly to your travel destination. Unlike granular absorbents, transport of the cartridge does not raise hazmat objections by carriers and often costs less to ship.

Is a granular absorbent option available for the O2ptima?

There is currently no manufacturer approved granular absorbent option for the O2ptima.

Does the O2ptima have a CO2 monitor?

No. CO2 monitoring is a 'bleeding edge' technology that will begin to appear in recreational rebreathers in the next few years but as a practical matter the merits of CO2 monitoring are unproven. You should not confuse a CO2 monitor with the breathing loop temperature monitor or the scrubber temperature monitor offered by rebreather manufacturers. The temperature monitor does not provide any information or warning regarding actual CO2 levels in the breathing loop.

Does the O2ptima-SR support an external PO2 monitor and backup dive computer ?

We offer a HUD upgrade to provide a Shearwater NERD heads-up-display rather than the LED display or can deliver your O2ptima-SR with a factory installed external PO2 monitoring cable for an optional Fischer 103 connector compatible CCR dive computer such as the Shearwater Petrel-EXT. The additional dive computer provides independent triple redundant monitoring of PO2, as well as redundant depth/time and decompression status.

What cylinders should I use with the O2ptima?

The O2ptima will accept a variety of cylinder sizes using standard left and right modular DIN valves. Including the valve, the maximum cylinder dimensions are { 18.5 in | 46.99 cm } in length by { 5.5 in | 13.97 cm } in diameter. For O2ptima "Sport" configurations I suggest aluminum 13 cubic foot (2L) capacity cylinders, which minimizes the O2ptima total weight. The 13's are more than adequate to support over four hours of sport diving, but with the 13's you should carry an external bailout. The O2ptima may also be configured with aluminum 20 cubic foot (3L) cylinders. With the additional volume of the AL-20 cylinders, diluent capacity is sufficient to support on-board bailout for the sport diver, and provides plenty of oxygen capacity even with transfer under filling. Some cold water drysuit divers prefer the addtional weight of steel LP27 (4L) cylinders.

Why is the O2ptima oxygen cylinder pressure gauge (SPG) always graduated in metric BAR?

The oxygen (O2) gauge is always in BAR to make it easier to compute the divers carbon dioxide (CO2) production because there is a very simple relationship between pressure in BAR and the volume of the cylinder, the volume of O2 gas expended and the volume of CO2 produced. Given the Extendair cartridge is rated to absorb 240 liters of CO2 and assuming that 1L of O2 expended will produce 1L of CO2 then when 240L of O2 supply gas has been expended the absorbent must be changed. Using this simple relationship it is possible to more accurately predict the useful life of the absorbent based on the divers actual metabolic rate and actual work effort on the dive rather than just a standardized three hour time limit.

What BC should I use with the O2ptima?

Use whatever backplate and harness style system you prefer; my personal preference is for the very comfortable Dive Rite TransPac. I like to add the Dive Rite Tech Buttplate and sidemount my bailout using ring bungees. I like the Dive Rite Nomad XT wing because of the peculiar way I prefer to position my BC inflator hose, but I generally recommend the Dive Rite CCR Wing, because it has a shape and features that work well with the O2ptima and offers very low drag. The CCR wing offers { 50 lb | 22.68 kg } of lift and technical divers should consider the redundant bladder option.

What accessories should I buy for my O2ptima-SR?

I recommend learning on the base factory configuration and avoiding accessories or aftermarket modifications until you have some experience with your rebreather. Divers new to rebreathers often 'surf the boards' and develop the idea that there are many needed 'improvements' to the factory configuration for their chosen rebreather. Some of these changes and addons are open-circuit mindset solutions in search of a closed-circuit problem that doesn't exist, some are just tradeoffs of one benefit for another, some will have merit for specific types of extreme diving but may be counter productive in the beginning, and a few are just plain unsafe. The base O2ptima is pretty much complete, you need only add your choice of cylinders and bailout to be ready to dive. Go slow, build experience and then gradually make additions or modifications.

What is the O2ptima maximum dive time and depth?

Rebreathers carry many hours of breathing gas regardless of depth. The O2ptima can accept auxiliary outboard plug-in gas supplies as well, so dive time is no longer limited by gas volume. As with most rebreathers, the O2ptima diver is typically limited by the duration of the CO2 absorbent, so multi-hour runtime dives are routine. As with open-circuit nitrox diving, rebreather divers must also track their decompression and oxygen exposure; depending on the dive profile these may also limit the dive time. The O2ptima rebreathers are suitable for diving at all sport depths and have been tested to a depth exceeding 300 feet. There are some individuals who routinely dive the unit that deep and deeper. Although the rebreather can function at depths much deeper, there are numerous additional considerations. The O2ptima rebreather is a popular choice for divers who wish to dive to extremes.

Is the O2ptima capable of diving with mixed gases?

Yes, the O2ptima as delivered can use either nitrox or trimix diluents that may be either hyperoxic, normoxic or hypoxic. Because the O2ptima is a fully closed-circuit design, the use of mixed gas diluents is very inexpensive compared to open-circuit. Personally, I recommend and teach rebreather divers to substitute normoxic trimix diluent (21% oxygen, 35% helium) rather than air even within recreational sport limits for the benefits of reduced narcosis, improved work of breathing, and improved scrubber function. However, use of anything other than normoxic diluent or diving outside of recreational sport diving limits requires significant additional diver training.

Does the O2ptima take a long time to maintain?

Yes and No. Many rebreather sport divers, including O2ptima divers, find they spend noticeably more time on equipment compared to open-circuit because the rebreather diver must always be careful and disciplined about maintenance. However, compared to most other rebreathers the O2ptima takes less time to setup, in part because of the cartridge. If you have been habitually careful with your open-circuit dive equipment and treat your equipment with respect, as an experienced O2ptima sport diver you will spend only slightly more time with your O2ptima maintenance than you did with open-circuit.

How well does the O2ptima travel?

The O2ptima is one of the most travel convenient rebreathers available. A key design goal was to minimize size/weight and divers are able to travel by air with the O2ptima as carry-on luggage in most circumstances. Regardless of the brand of rebreather it can be annoying to travel with cylinders because they are carefully examined by security personnel, and occasionally even confiscated. You may prefer to rent cylinders at the destination or ship the cylinders ahead by a package carrier such as UPS or DHL.

How is an O2ptima different from other rebreathers?

All of the major rebreather models are good quality units. There is no perfect rebreather; they all have strengths and weaknesses that make each uniquely more or less suited to your needs. Beyond the features of the rebreather itself, you should consider the supplier along with how the model was designed and has been supported. Only a very few rebreather models are supplied by well-established companies. As an independent dealer, we stock O2ptima spares and consumables with online ordering and same day shipping.

Is the O2ptima rebreather safe?

No type of rebreather can be said to be categorically safer than another. Statistics suggest closed-circuit rebreather diving is five to ten times higher risk than open circuit scuba. The quality of training may be the most significant factor affecting rebreather safety. No rebreather is foolproof, and the fact remains that compared to open circuit there is a disproportionate number of rebreather fatalities, many of which have been attributed to diver error. Your safety while diving is controlled by you, not by your rebreather.

Last Updated: 19-Mar-2015